UK CBAM – Full Implementation from 2027: What Companies Need to Know Now

The United Kingdom goes straight into the operational phase

On 1 January 2027, the United Kingdom will fully implement its Carbon Border Adjustment Mechanism. There will be no transitional phase, no grace period, and no reporting-only obligation without payment. From the very first import of covered goods, importers must declare embedded emissions and pay the corresponding levy. Penalties will be possible from day one. The legislation is still in draft form, but the basic structure is set. HMRC, as the competent authority, will clarify operational details later this year. The measure is part of the UK’s net zero pathway. As with the EU CBAM, its aim is to prevent carbon leakage by creating a level playing field between domestic producers already bearing CO₂ costs and importers of goods from potentially more carbon-intensive production processes. Companies therefore have less than eighteen months to prepare systems, supplier agreements, and data processes to ensure full compliance from day one.

Scope and specific features

At launch, the UK CBAM will apply to aluminium, cement, fertilisers, hydrogen, as well as iron and steel. Coverage is not defined by general sector labels but by specific customs tariff codes. Correct customs classification is therefore not just a technicality but the foundation of compliance. Misclassification can result in overlooked obligations and retrospective payment demands from the authority. Alongside electricity, certain goods within these sectors-such as specific scrap imports for aluminium as well as iron and steel-are explicitly excluded. Since the EU CBAM appears to have served as the blueprint for UK legislation, it will be interesting to see to what extent the EU’s plans for scrap monitoring will influence any future inclusion of scrap under the UK CBAM. The EU is currently examining this issue closely in the context of preventing so-called resource shuffling.

Data requirements and verification

For all CBAM goods, both direct and indirect emissions must be reported. Where actual emissions data are used, these must be independently verified by an accredited body before submission. In practice, this means that companies relying on supplier data should initiate early discussions on verification, timelines, and costs. If no actual values are available, government-set default values per product category and net weight can be used. While default values simplify compliance, they do not allow companies to reflect below-average emissions in the levy calculation. For sourcing from lower-emission production routes, this can be a decisive disadvantage.

Credit for foreign carbon pricing

CBAM obligations can be reduced if a CO₂ price has already been paid in the country of origin and is recognised by the UK as equivalent. The decisive factor is the effective CO₂ price after deduction of any free allocations or rebates. This is critical: a nominally high CO₂ tax rate can be substantially eroded by free allocations, thereby also reducing the relief granted in the UK. Without verified evidence, however, the authority will not grant any deduction. The risk of double charging increases.

Threshold and registration requirement

The UK CBAM provides for a de minimis threshold of GBP 50,000 for CBAM goods, calculated on the basis of customs value. Two tests apply in parallel. The retrospective test sums the value of CBAM goods imported over the previous twelve months. The forward-looking test estimates whether imports in the next 30 days will exceed the threshold. If either condition is met, immediate registration with HMRC is required. This creates an ongoing compliance requirement, as companies must continuously monitor both past and planned shipments.

Reporting obligations and deadlines

The first reporting period runs from 1 January to 31 December 2027. Reporting and payment are due by 31 May 2028. For this payment deadline, the EU recently concluded-within the framework of its Omnibus initiative-that the time left for companies to gather actual emissions data is too short. It remains to be seen whether the UK will make similar adjustments. From 2028, settlements will be quarterly with a two-month deadline for reporting and payment. Even if no CBAM liability arises in a given period, registered importers must submit a nil return. This keeps the authority’s dataset complete but may catch out companies that do not actively track their registration status.

Outlook

The UK CBAM will integrate climate costs directly into cross-border trade in carbon-intensive goods. For many companies, the main challenge will be less about making the payment and more about building the structures to do it correctly and on time. Reliable and, where required, verified emissions data will become a valuable part of the supply chain. By contrast, incorrect customs classification or overlooked thresholds will create compliance risks. Companies that now begin identifying affected goods, engaging suppliers, and setting up systems for ongoing threshold monitoring will not only avoid last-minute disruptions but also reduce costs through cleaner sourcing and better data.

Support with planning

If you would like to know how much your company will be affected by the UK CBAM and how to set up efficient compliance processes, please contact me directly at helge@kolum.earth. Together, we will ensure you are fully prepared in time.